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Australian scientists are on a mission to find out why wind turbines might be making some people sick.

Known as wind turbine syndrome, the noise generated by wind turbines can affect people kilometres away, causing complaints including headaches, dizziness, high blood pressure, and lack of sleep.

In an effort to develop a quieter wind turbine, researchers led by Dr Con Doolan of the University of Adelaide School of Mechanical Engineering are investigating the causes of this noise.

According to Doolan there are different types of noises generated by wind turbines.

"The strongest is aerodynamic noise caused by air passing over the turbine rotor blade trailing edge. It's a high frequency noise called blade swish which generally goes up and down in amplitude," he says.

"It's highly focused, radiating more strongly in some directions than others, but usually forward of the blade as it spins."

"There are also atmospheric effects that can cause the noise to propagate differently in different directions. So downwind propagation is different to upwind propagation, and it's different on each side as well."

More research needed

Considering how long wind turbines have been around, Doolan was surprised there isn't a better understanding of the effects of noise generated by wind turbines.

"We don't yet understand exactly how turbulence and blade edge, or boundary layer, interact and how that makes the noise louder."

Doolan's team are developing a computer model using wind tunnels and arrays of microphones, sensors and lasers to study the science behind these effects and assess different designs that may help noise reduction.

He also wants to know how multiple turbines on wind farms appear to worsen the problem.

"If you take traditional noise measurements such as decibel readings it shouldn't be too much of an issue. But people across the world are complaining and their symptoms are all similar," says Doolan.

"There seems to be something there and we think it's got something to do with the character of the noise, the way it goes up and down."

Doolan says as we move towards more renewable energy sources, we can expect to see more wind farms in the future.

"That means more people will be exposed to wind farms, so we need to understand why some people are more affected than others."

"With the right funding we could get some definitive results in two to three years which will help us plan better wind farms in the future."